Microfluidics systems promise tremendous improvements in quality, rapidity and cost outlay, as compared with macroscopic systems, when chemical mixing and reaction processes are being performed, since the reaction and dwell times in the fluid paths of microfluidics systems are very short and only very small substance quantities are used and processed with high accuracy and in a reproducible way. Consequently, especially in industrial production, the quantity, throughput and productivity requirements can be satisfied, the fluid paths (mixing or reaction branches) have to be connected in parallel, where appropriate in large numbers (numbering-up).
Depending on the application, the parallel connection may be such that a plurality of identical microducts are each formed and connected in parallel in microfluidics components, for example a mixer or reactor, or such that entire microfluidics components or systems composed of microfluidics components are multiply connected in parallel. By means of suitable microengineering methods (for example, etching methods, LIGA technology or micromechanics), the parallel fluid paths can be produced identically with high precision, so that the same process conditions, such as pressure, temperature, mass throughflow, etc., should each prevail in all the parallel-connected fluid paths and therefore the same products can each be obtained from all the parallel mixing or reaction branches and be merged without losses of quality. This also presupposes, however, that all the parallel-connected mixing or reaction branches are supplied with the same volume flows of starting materials. Here, the problem arises in that microfluidics systems are inclined to operationally induce variations in the effective throughflow resistance due to blockages of the fluid paths. Thus, for example, reaction products may stick as solids to the duct walls (i.e., fouling), which increase the pressure drop across the reaction branch, and then become loose again. As a result, the pressure drop decreases abruptly. This behavior may occur cyclically and to a different extent or at different times for each reaction branch. Whereas in macroscopic systems, for example, the mass throughflow can readily be measured, virtually fault-free, and be delivered to a throughflow control, this is not possible at a justifiable outlay for the individual fluid paths in the case of parallelized microfluidics systems.
EP 1 510 255 A1 discloses a microfluidics system for mixing at least two starting materials having a single mixing or reaction branch, in which a number of supply ducts which corresponds to the number of starting materials issue into a mixing or reaction duct. Here, each of the supply ducts include an intake line for each starting material, an for each supply duct, a valve circuit between each intake line of a starting material, where the supply ducts for a respective starting material and a injection pumps are provide to each respective supply duct. Here, the injection pump consists of two individual injectors, one of which sucks material and the other of presses material. In addition, the valve circuit is designed for connecting the injection pumps, in a first valve position, to the intake line and connecting them, in a second valve position, to each assigned supply duct.
US 2005/0232387 A1 discloses a microfluidics system for mixing two starting materials, in which two injection pumps convey the starting materials through two supply ducts into a mixing or reaction duct. Furthermore, US 2005/0232387 A1 discloses a valve circuit for the continuous conveyance of the respective starting material and for filling the respective injection pump, consisting here of two individual injectors. Here, the valve circuit is designed, in a first valve position, to connect one of the two injectors to an intake line for the respective starting material, in a second valve position to shut off said injector and, in a third valve position, to connect it to the supply duct and to the other injector located on the latter.
EP 0 299 658 A2 discloses a system for mixing at least starting materials, in which two injection pumps driven synchronously by means of a common drive intake in the starting materials from reservoirs by valve arrangements and subsequently convey them through two supply ducts into a mixing unit.
DE 20 2005 007 485 U1 discloses an arrangement for metering fluids by means of injection pumps and valves, assigned to these, for changing over between fluid uptake and fluid discharge.
Here, a plurality of the injection pumps may be operated in parallel by a single drive.
DE 103 41 110 A1 discloses a mixing and metering section which is formed by microengineering on a chip and which is filled with the starting materials via valves by an injection pump.